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arXiv 1902.01322math.COcs.DM
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二部图的圈宽和完美匹配宽度的网格定理

Cyclewidth and the Grid Theorem for Perfect Matching Width of Bipartite Graphs

Meike Hatzel, Roman Rabinovich, Sebastian Wiederrecht

摘要:

一个连通图G称为匹配覆盖图,如果G的每条边都包含在一个完美匹配中。完美匹配宽度是基于分支分解的匹配覆盖图的宽度参数。它是由Norine引入的,旨在作为匹配覆盖图的结构研究的工具,特别是在Pfidian方向的背景下。Norine指出,高完美匹配宽度的图将包含一个大的网格作为匹配子图,类似于Robertson和Seymour关于树宽的结果。在本文中,我们获得了自完美匹配宽度引入以来的第一个结果。对于二部图的限制情形,我们证明了完美匹配宽度等价于有向树宽度,从而证明了Kawarabayashi和Kreutzer关于有向\treewidth的有向网格定理蕴含了Norine猜想.

英文摘要:

A connected graph G is called matching covered if every edge of G is contained in a perfect matching. Perfect matching width is a width parameter for matching covered graphs based on a branch decomposition. It was introduced by Norine and intended as a tool for the structural study of matching covered graphs, especially in the context of Pfaffian orientations. Norine conjectured that graphs of high perfect matching width would contain a large grid as a matching minor, similar to the result on treewidth by Robertson and Seymour. In this paper we obtain the first results on perfect matching width since its introduction. For the restricted case of bipartite graphs, we show that perfect matching width is equivalent to directed treewidth and thus the Directed Grid Theorem by Kawarabayashi and Kreutzer for directed \treewidth implies Norine's conjecture.

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